Jean-Louis came to see me with his solar bike, he lives a few kilometers from my house and I didn’t know it!
He’s a good handyman: equipped with a lathe, he made all the aluminum parts he needed, he built and programmed a databox. Sporty and active in the associative world, he has no time to be bored.
His next project: building a solar trike.
Congratulations Jean-Louis!

Visits: 254

From my first participation in the Sun Trip in 2017 until today, I have experimented with different configurations of solar bikes.
Here are the basic principles that guided my constructions:
– from 2017 to 2019, I wanted to be able to take my vehicle by train. So I opted for a classic bike associated with a single-wheel trailer carrying the solar panels (which could tilt vertically).
– for the Sun Trip 2020 which was to take us to China, my goal was to be able to have as much solar energy as possible. So I associated my solar trailer (3 panels) with a recumbent bike on which I added a solar roof (2 panels). Thus, I reached the maximum solar surface accepted on the Sun Trip (almost 2.5 m² which corresponds to a power of 500Wp). In 2021, I transformed the trailer a bit.

Année	Remorque	Solaire	Moteur	Photo
2017	Extrawheel modifiée	200Wc	BionX
2018	DIY fabrication 2018	200Wc +100Wc à l'arrêt	Crystalyte SAW (roue avant vélo)
2019 juin	DIY fabrication 2019	300 Wc	Crystalyte SAW (roue remorque)
2019 juillet	DIY fabrication 2019	300 Wc	9Continent RH205 (roue arrière vélo)
2020	DIY fabrication 2020	500 Wc	9Continent FH212 (roue avant vélo)
2021	DIY évolution 2021	500 Wc	9Continent FH212 (roue avant vélo)

Visits: 386

Installing signs on a bicycle raises many problems. The solutions are many and varied, as we can see during the various Sun Trips.
The designer is led to make choices, according to his priorities, his taste and his budget.
Most often, priority is given to a type of bike (classic, recumbent, cargo bike, trike …) the solar equipment will then have to adapt to it.

But sometimes, other constraints are chosen as priorities and guide the design:
– have a large solar surface, to capture a maximum of energy,
– have a large capacity battery, to store more energy in poor weather,
– design a very light vehicle to easily climb the mountains,
– design a very solid vehicle, to avoid breakage during long journeys,
– have a foldable vehicle easily for transport.

We dream of the ideal vehicle, light, solid, powerful, with a long range. Very quickly, you realize that all these wishes conflict with each other. Increasing the surface area of ​​the panels and the supporting structure contributes to weighing down the vehicle. Likewise, with increasing battery capacity. Lightening the vehicle as much as possible can make it too fragile to face the road and vibrations.

Since 2017, I wanted to have a vehicle that can be taken by train: I opted for a classic bike and a folding single-wheel trailer. In 2018, I tested a folding bike with a foldable trailer to be able to take the vehicle on international buses. The maximum area of ​​panels that I managed to install on a trailer was 1.5m², corresponding to a power of 300Wp.

I have not explored the possibility of installing panels on the bike, on the roof, as did Daniel Jeni during the Sun Trip 2018. Maybe I would try this idea one day?

Preparation of the Sun Trip 2020 Lyon-Canton

I wanted to have the maximum authorized solar surface, 2.5m². For this I first considered using a cargo bike and then a tandem.
Finally, it was thanks to Guillaume Devot of Déclic Eco that the idea of ​​using a recumbent bike came to life. Installing 1m² of panels on the bike completes the 1.5m² of trailer panels.
But a concern remained: would this configuration be easy to drive on the road, even in the case of a strong side wind? Experience has shown me that it is.

It remains for me to test the efficiency and solidity of the supporting structure of the panels on the bike.
The trailer structure has proven itself in 2018 and 2019 over 6000 km. It’s reassuring because I could observe that the vibrations and shocks of the road, over thousands of kilometers, really test the load-bearing structure of the panels.

For learn more about choices adopted by other participants in the various Sun Trips …

Visits: 443

Partie	Éléments	Poids	Total
Vélo	Vélo Nazca Pioneer, pneus Schwalbe Marathon Plus Tour, moyeu Rohloff		25,5 kg
	Moteur Nine Continent FH212	6,0 kg
	Contrôleur	0,3 kg
	Batterie	5,5 kg
	Panneaux (2)	1,6 kg x 2
	Cornière alu, tube horizontal, supports verticaux	0,9 kg x 2 0,9 kg x 1
	Régulateurs solaires	0,29 kg x 1 0,46 kg x 1
	Câblages	0,30 kg
Remorque	Timon Bob Yak	1,30 kg	20,8 kg
	Structure remorque	5,00 kg
	Roue	1,35 kg
	Planche bagage	0,55 kg
	Panneaux solaires	1,50 kg x 3
	Cornières alu, traverses bois, tube carbone kevlar	4,15 kg
	Régulateur solaire (1)	0,29 kg x 1
	Régulateurs solaires (2)	0,46 kg x 2
	Système d'inclinaison	0,80 kg
	Câblage	0,30 kg
Sacoches et bagages			12,5 kg
Total			58,8 kg

Visits: 78

Solar panels cannot be connected directly to the battery, they must be connected through a solar regulator.

3.1. Solar regulator

This is responsible for adjusting the voltage to that of the battery (36 or 48 Volts for example) and modifying the current (Amps) according to the amount of light energy supplied by the sun.
The most common type among solar cyclists is the MPPT “boost” technology regulator.
The regulator’s MPPT technology ensures the best possible efficiency in the conversion of electrical energy. The qualification “boost” means that the voltage of the panels at the input of the regulator must be lower than that of the battery and the regulator then adjusts the output voltage to that of the battery.

3.2. Solar panels

Technology
The preferred panels are flexible monocrystalline silicon panels: they are light and have a good conversion efficiency of light energy into electrical energy. Better to forget the models developed for the roofs of houses, in polycrystalline silicon (very heavy, lower performance).

Article: how to choose your solar panels

Format
The solar bike builder will have to choose the format of his panels according to his bike and the structure planned to support them.
To participate in the Sun Trip, the width of the panels must not exceed 1 meter which corresponds to 7 photovoltaic cells (in the costing dimensions of 12.5cm x 12.5cm). But the traditional formats have rather even numbers of cells, in practice, a majority of solar cyclists now have panels of 6 cells in width.

2 cells =28cm	4 cells =54cm	6 cells =80cm

The length of the panels will depend on the bike chosen, or the trailer …
Warning: the size of the panel has a direct influence on its electrical characteristics, it is advisable to ensure the adequacy between panels, regulators and battery.

Quality
The quality of a panel, in terms of electricity production, depends a lot on the quality of the photovoltaic cells that constitute it. In the technical sheet, the mention of a major cell manufacturer is a guarantee of quality.
However, the big manufacturers sort their cells and sell them in different quality grades. But this clue is never mentioned by the panel manufacturer.

Article: the performance of a photovoltaic cell

Article : comparative performance test of 3 solar panels

3.3. Support structure for solar panels

How to transport solar panels on a bicycle? This is one of the important questions that the solar cyclist asks himself. This question is also related to the surface of panels that one wishes to install.
If installing 1 panel of 0.7 m² is quite simple, installing 2.5 m² of panels is much more complicated.

Article: install solar panels! Yes but how?

Article: the installation of panels solar on my bikes

Visits: 118

The electrical assistance system includes at least a battery, a motor, a motor controller (sometimes integrated inside the motor), a control and display console. Other elements can be added: pedaling sensor, torque sensor, speed sensor, handlebar accelerator …

2.1. The battery

As explained in Part 1, the batteries supplied with some commercial bicycles cannot be charged during use, which greatly complicates their integration into a solar bicycle.

Battery specifications
The main characteristics of a battery are:
– chemical technology: today, most bicycle batteries use Litium-Ion technology.
– the nominal voltage: 36 Volts, 48 ​​Volts, or even 52 Volts,
– the capacity, expressed in Ampere-hours or in Watts-hours. This value reflects the amount of energy that the battery is able to store and restore.

Components of the battery
A battery is made up of a set of Li-Ion elements (called “cells”) associated in series and in parallel, to which an electronic protection system (BMS) is added. The role of the BMS is to prevent too deep a charge or discharge and to balance the voltages between the Li-Ion cells.
Most batteries are made up of cells called “18650”, with reference to their physical format (diameter = 18mm, length = 65mm).

Association of cells in series
The nominal voltage of an 18650 cell is 3.6 Volts.
To make a 36 volt battery, we put 10 cells in series.

For a 48 battery Volts, the series has 13 cells.

Association of cells in parallel
Manufacturers offer 18650 cells in different capacities: 2000, 2500, 2900, up to 3500 Milliampere-hour.
In the example shown below, we have chosen 3500 mAh cells. The set includes only 1 series, its overall capacity is 3500 mAh or 3.5 A-h.

In the second example shown below, still with 3500 mAh cells, 4 series of 10 cells have been associated in parallel. The resulting battery has an overall capacity of 14 A-h.

High capacity cells (3500 mA-h) are often the most expensive, but their advantage is that they can store more energy at equal weight. In other words, at equal capacity, the battery will be lighter, which is an advantage for the solar cyclist.
As for the quality of the cells (capacity, longevity), it is often better among large manufacturers such as LG, Samsung, Sanyo …

2.2. The engine

There are different types of engines, each with advantages and disadvantages. Knowing them will be an asset in making the best choice according to the intended use.

2.2.a. The Direct Drive “wheel” motor

It is inserted into a wheel instead of the hub, this Direct Drive type has no gears inside. There are models for front wheel or rear wheel. Front wheel models can optionally be installed on a trailer.
Benefits: very reliable, no maintenance. On descents, the motor can brake and regenerate electricity to recharge the battery.
Disadvantages: heavier than the reduced motor, and less efficient on very steep hills where it gets hot.

2.2.b. The reduced “wheel” motor

It is inserted into a wheel instead of the hub, it has gears inside. There are models for front wheel or rear wheel. Front wheel models can optionally be installed on a trailer.
Benefits: smaller engine, less heavy, often more efficient than Direct Drive on hills. . It does not brake the bike when pedaling without assistance.
Disadvantages: Gears to be regularly maintained and changed after long distance trips. No regeneration on descents.

2.2.c. The “pedal” motor

This motor is inserted in place of the original crankset, it has gears inside.
Benefits: smaller engine, less heavy, very efficient on hills. It does not brake the bike when pedaling without assistance.
Disadvantages: Gears to be regularly maintained and changed after long distance trips. No regeneration on descents.

2.3. The motor controller

Depending on the system, the controller can be independent or integrated into the engine block. It is very often independent in wheel motor systems and often integrated into pedal motors. Its role is to manage the energy supplied to the motor, as a function of several data (level of assistance chosen, speed, energy available in the battery, signal from the torque or pedaling sensor, etc.).

2.4. The control and display console

It gives indications to the user (eg: speed, level of assistance, battery voltage, distance traveled, etc.) and, moreover, it allows him to communicate with the system (at least to choose the level of assistance).

In advanced systems, such as those manufactured by the company Grin Technologie, the Cycle-Analyst console, allows the display and selection of a very large number of parameters: speed, power consumed, assistance levels, etc. additional equipment allows simultaneous display of solar production. It is thus possible to know in real time the amount of energy consumed and produced.

In the photo above, we can see that the consumption by the motor is 353W at this precise moment, while the solar production is 371W.

2.5. The pedaling sensor or the torque sensor

Depending on the system, this sensor may be separate or integrated into the engine block, in which case it is not visible. The most advanced systems have a torque sensor that measures the power given by the cyclist, the others a pedaling sensor that measures the cyclist’s pedaling pace.

2.6. The speed sensor

Depending on the system, this sensor can be separate or integrated into the engine block.

2.7. The handlebar accelerator

It is an optional accessory. It is authorized in France only for starting, for example after a red light. It is often very useful, especially on recumbent bikes, for hill starts.

Visits: 90

A solar bicycle is made up of the following components: a bicycle, sometimes combined with a trailer, an electric assistance system, and solar equipment.
We will describe these elements below, and consider the different possibilities available to those who want to build their solar bike.

1. The bike

It is possible to use either to use a commercial electric-assisted bicycle, or to use a conventional bicycle to which an electrification kit is added.

1.1 A commercially available electrically assisted bicycle

In this case, be aware that many major manufacturers prevent the user from recharging the battery while the engine is running. This then requires having 2 batteries: one is recharged by the solar panel while the other supplies the motor, which means that the batteries must be replaced periodically. We understand that this system is not the most practical.
In addition, some manufacturers even prevent charging the battery other than by connecting it to the mains charger, which further complicates the task.
But some rarer commercial bikes do not have these limitations and can be easily converted into solar bikes.

1.2 A simple bike to which we add electric assistance

On reading paragraph 1.1, we understand that it is often easier and more efficient to install an electric assistance system on a non-electric bicycle.
Two ways to proceed:
– either by purchasing a complete kit (advantages: simplicity / disadvantages: if the system is “proprietary”, the user cannot use parts from another brand),
– either by composing a kit, by choosing each element (advantages: the choice of each element is much wider, you can better adjust the elements to your own needs, to your practice / disadvantages: the range of possibilities can confuse the beginner).

To read: note from the Directorate of Legal and Administrative Information (Prime Minister): https://www.service-public.fr/particuliers/actualites/A14325

1.3 Different types of bikes possible

The choice of the bicycle is important because it will often condition the way of installing the solar panels, on the bicycle itself and / or on a trailer.
Many types of bikes have been tried out, according to individual tastes:

• classic upright bike with trailer, 1 or 2 wheels,
• classic upright bike with solar roof,
• straight-lying tandem transformed,
• cargo bike, with panels on the bike or on the roof,
• recumbent bicycle with panels on the roof, and sometimes in tow,
• trike, tandem trike, with panels on the roof, and sometimes in tow,
• velomobile with panels on the roof, and sometimes in tow.

See the different types of bikes on the Sun Trips since 2013.

Visits: 95

It was at the Sun Trip 2019 and 2020 preparation weekend that I discovered this innovation. Thanks to Ralf!
So I decided to replace the BMS of my battery (battery management system) by a model with a bluetooth communication device. It cost me about thirty euros and a little more time than I imagined for the installation. Indeed, the connection pads of the BMS were different and I had to use the soldering iron.

No matter, I am satisfied with the result: now, I can know everything about the status of my battery, in real time, on the dedicated smartphone application. I still added a switch: it allows me to turn off the bluetooth module to avoid unnecessary discharge of the battery, for example during winter storage.

Visits: 102

Apparently nothing has changed between the March version and the April version 3.1. I simply changed the 3 solar panels! I replaced the old economics panels with high quality panels, made of the latest Sunpower ™ Maxeon photovoltaic cells, in the highest “class” or “grade”. Indeed, after manufacture, the cells are sorted into different classes according to their performance (Sunpower ™ uses a particular classification with well over 4 classes).

Result: 86% more solar energy for the same surface! What a difference !

I realize that in 2018 I thought to ride with 200Wc but in fact I had only 107Wc real. To have the same power, only 1 of the new panels would have been necessary, my trailer would have been 2 times shorter, lighter, hyper-manageable. In 2019, I chose to increase the panel area for more power. I wish: – to have more autonomy in case of cloudy weather with clearings, not to be worried about finishing a day “on the pedal”, – to ride faster if necessary, – to ride longer to travel greater distances.

Visits: 177

Previous editions of the Sun trip have seen a wide variety of bikes: Classic straight bikes, tandems, but also recumbent bikes, recumbent tricycles, tandem-lying tricycles, cargo bikes, a seated/reclining tandem and, for a short appearance, a family bike with 4 wheels…
But no mobile bikes had yet participated. This will be the case this year with Bertrand Touzet: on July 6, he will start the Sun trip tour 2019 with his mobile bike whose fairing improves aerodynamics.
Bertrand makes us discover his vehicle in this short video:

Visits: 140

This week, I installed new, very good quality solar panels on my bike. Their real power is 86% higher than that of my old panels. I went from Solarduino Bike 3.0 to version 3.1!

How much did my new 2019 solar bike cost?
I counted the different elements used. I acquired some for the first project in 2017, others in 2018 and 2019. Here is the summary:

The cost of the trailer may seem trivial, the reason is that I mainly used salvage parts (fork and bicycle frames) acquired in the participative workshop La Rustine in Dijon.

Visits: 98